The fabrication of large structures may involve the performance of large numbers of manufacturing operations, such as the drilling of a large number of holes in the components of the structure. Conventional structures that require a large number of drilling operations include, for example, aircraft, missiles, ships, railcars, sheet metal buildings, and other similar structures. In particular, conventional aircraft fabrication processes typically involve the drilling of a large number of holes in wing sections of the aircraft to allow these sections to be attached to each other and to the airframe with fasteners (e.g. rivets). Other types of manufacturing operations that may be involved in the construction of structures include riveting, cutting, welding, sanding, measuring and inspecting operations.
A variety of devices have been developed to facilitate drilling operations involving the drilling of a large number of holes. For example, U.S. Pat. No. 4,850,763 issued to Jack et al. discloses a drilling system that includes a pair of rails temporarily attached to an aircraft fuselage. A support carriage is slideably coupled to the rails and supports a drill assembly. A template attached to the aircraft fuselage provides an index of the desired locations of the holes that are to be formed in the aircraft fuselage. As the carriage is moved along the rails, a locking mechanism (or trigger) interacts with the template to securely position the carriage for a subsequent drilling operation.
Although desirable results have been achieved using the prior art drilling systems, some disadvantages have been noted. The drill assemblies that are conventionally used for such operations typically weigh approximately twenty pounds, and may be relatively bulky and awkward to handle. These attributes may lead to operator fatigue, and may reduce the efficiency of the fabrication process. Furthermore, the weight and bulk of the drill assembly may cause the supporting assembly of the rails and the carriage to sag, twist, or bend, depending on the orientation of the fuselage section under work, which may result in inaccuracies or misalignment of the resulting holes. For the foregoing reasons, an unmet need exists for an improved support assembly for performing manufacturing operations, including drilling operations.